Abstract
A reflection and penetration problem of photons from a plane monodirectional beam normally incident on semi-infinite medium of water has been solved by Monte Carlo method. Secondary radiation spectra and their integrating resultant number fluence, energy fluence, and dose (exposure) buildup factors as well as depth doses of a variety of field size are presented for the source energy from 200 to 25 keV at the depth up to 5 mean-free-paths. Photoelectric effect, coherent scattering, and incoherent scattering were taken into account as an important process for these energies photons in water. A comparison of the present results with those published in literature shows generally good agreement except for the source energy of 100 keV, though it deteriorates at deep penetration.
